The Porter-Lawler theory of motivation

Actual performance in a job is primarily determined by the effort spent. But it is also affected by the person’s ability to do the job and also by individual’s perception of what the required task is. So performance is the responsible factor that leads to intrinsic as well as extrinsic rewards. These rewards, along with the equity of individual leads to satisfaction. Hence, satisfaction of the individual depends upon the fairness of the reward.
Source: http://www.laynetworks.com/Theories-of-Motivation.html